This invention relates to a configurable electronic control unit designed to perform control functions in a wide variety of applications. The applications range from the control of appliances to implementation of control functions in commercial, industrial and automotive environments. Some examples of applications are refrigerators and washing machines in the field of appliances, HVAC (Heating, Ventilation and Air-Conditioning) and security controls in residential and commercial environments, and passenger compartment climate control in the automotive area. The controller is configurable in a variety of ways to provide flexibility and optimisation of control in the intended application, at low cost.
Control systems are used to regulate the operation of a device or system in a desired manner. This activity, in most cases, involves the control of one or more physical parameters such as temperature, pressure, level, flow, position, speed, and the like. To perform such a function it is generally necessary for the control system to sense and measure the value of the physical parameters, compare the measured values with the requirement and then operate one or more actuation devices (e.g. motors, valves, heaters) to automatically adjust the values of these parameters to desired levels. Depending upon the physical parameters involved, various transducers/sensors are used to convert the value of the physical parameter to a signal suitable for processing by the control system. In electrical/electronic control systems the conversion is to a suitable electrical parameter e.g. voltage, current, resistance, while in electro-pneumatic or mechanical systems the conversion is generally to a suitable mechanical property e.g. presssure, displacement. The selection of a transducer/sensor for a specific application depends upon the physical parameter that is required to be measured as well as the type of signal to which the conversion is to be made.
Electronic controls provide inherent advantages over other types of controls, in the vast majority of applications. For this reason, electronic controls are replacing electromechanical and electropneumatic controls in an increasing number of applications. We shall therefore limit our analysis to electronic controllers and all subsequent references to controllers and control systems shall pertain to electronic controllers and control systems.
The various types of transducers/sensors have different interface requirements and produces output signals with different characteristics. The control system has to provide the necessary interface conditions required by each transducer and possess the ability to process the signals received from it. This makes it necessary for the control system to provide different interface signals for each type of transducer/sensor.
In like manner, the various output devices that are required to be actuated by the control system inorder to bring about the correction or xe2x80x9ccontrolxe2x80x9d of the sensed physical parameter, differ in their requirements for actuation DC motors and AC motors for example, have different drive requirements. In some applications using AC loads simple ON-OFF control of the load is required, while in other applications phase-angle control or integral-cycle control or integral half-cycle control may be necessary. Similarly, in controlling DC loads a simple ON-OFF control may be adequate while in other applications pulse-width-modulation output is necessary. Likewise, different types of power switching have differing requirements for operation. Triac-firing requirements are very different from the requirements for switching relays or contactors. For each case the electronic circuitry in the controller has to change inorder to provide compatibility.
User interfaces also exist in a wide variety of forms, each requiring differing interfaces to the electronic control system. Analog devices such as potentiometers, for example, interface differently from digital devices such as keyboards. Similarly, remote control devices require a special interface which varies depending on the type of remote control used-viz. radio-frequency, infrared, ultrasonic. Also display devices come in many varietiesxe2x80x94e.g. LED, LCD, vacuum-fluorescentxe2x80x94each type requiring different interface signals.
Several electronic control systems in use today are based on microprocessors/microcontrollers that use software/firmware for defining the operation of the system. However, the various options described in the preceeding paragraphs, are not implementable through changes in software. Therefore in present designs the desired options are achieved by modifying the design and providing circuitry for each case. This implies that a control system designed and made for one type of sensor/transducer will not work with another transducer/sensor without making significant changes to the hardware. The electronic circuitry requirements are different for each of the interfaces. What is therefore required is that the circuitry is tailored for each interface. This requirement is achieved in one of 2 forms in existing designs. The less expensive designs are xe2x80x9chardwiredxe2x80x9d for a particular set of interfaces. A different xe2x80x9chardwiredxe2x80x9d version is used for each combination of interfaces. This results in a number of xe2x80x9cmodelsxe2x80x9d or variants that differ only in the interface specifications. More expensive controllers, on the other hand, are designed in a modular fashion, with the input and output interfaces designed as separate modules. There are a number of different types of modules available, one for each of the various interface options. The controller can be configured for various interface options by installing interface modules as required. This configuration may also be changed as required. However, the modular construction still requires physical change of modules for converting from one interface option to another. This implementation generally comes at a significant cost, and is hence applied only to relatively expensive products.
An additional constraint of existing electronic controls which are typically designed around microprocessors/microcontrollers which are programmed to perform the desired control actions is that the microprocessors/microcontrollers are very limited in terms of interfaces. This limitation stems from the fact the architecture of these devices is compute-oriented rather than control-oriented. The actual environment of a control application typically involves the processing of a significant number of signals and devices (e.g. sensors, switches, motors, etc.) some of which are analog in nature. Consequently, a significant amount of circuitry is required in addition to the microcontrollerxe2x80x94such as latches, decoders, drivers, multiplexers, analog-to-digital converters, digital-to-analog converters, signal-conditioning circuitry, etc. Some more expensive microcontrollers are available today that incorporate some additional circuitry such as analog-to-digital converters. PWM circuits, etc. However, these devices also require substantial additional circuitry in the majority of applications as the internal circuitry is still quite limited and involves compromises with the implementation of other functions. As a result, the application does not realise the full benefits of an electronic solution. U.S. Pat. Nos. 4,158,759, 4,367,387, 4,399,352, 4,406,945, 4,431,893, 4,481,393, 4,504,716, 4,533,810, 4,367,387, and 4,504,716 are examples of such electronic controls for applications in various appliances.
Some reconfigurable electronic controllers are also known. U.S. Pat. Nos. 5,306,995, 5,412,291, 5,619,614, and 5,647,231 describe some reconfigurable electronic controllers. However, the inventions covered by these patents are limited to only washing machines and dryers, and are at the same time relatively expensive to implement as they make use of fairly computation-intensive algorithms utilising fuzzy-logic implementations on microprocessor-based hardware. The limitations cited above in the case of microprocessor-based implementations are also applicable to these inventions.
Some general-purpose reconfigurable hardware devices are also known. Generically known as Field programmable Gate Arrays (FPGAs), these devices provide configurable hardware at the gate-level. These devices can be used to construct a wide variety of hardware with different functionality. Some mixed-signal (analog and digital) programmable array devices are also now available. However, these devices are limited in the variety and number of analog functions that are available. Furthermore, both the FPGA and mixed-signal array devices are difficult to configure and use because the circuit elements provided in them are very basic elements that require a large number of interconnections between them to provide the desired functionality. Quite often it is not possible to achieve the desired interconnections in a device containing a sufficient number of circuit elements and a larger and more expensive device has to be used. These limitations arise because the programmable array devices are designed as extremely general purpose devices, and are not oriented towards any specific area of application.
What is therefore required is a device that is designed for the specific requirements of control applications, including the requirements of interfacing to input and output devices in a variety of different ways, using an appropriate set of circuit elements in an arrangement that is configurable for any of the desired functions.
The object of this invention is to provide a control element which is designed to to be configurable for a wide variety of control functions including the configuring of both analog and digital input, output, user and power supply interfaces, as required, with minimal physical changes, and at low cost.
To achieve the said objective this invention provides an electronic controller comprising control circuitry for providing control functions, and output interface circuitry for providing output signals for controlling one or more load devices, characterized such that the said control circuitry and the said output interface circuitry are designed to be configurable for various control functions and various interfaces respectively, by means of configuration data supplied by a configuration memory included with the said electronic controller.
The said electronic controller includes input interface circuitry connecting to one or more analog or digital input devices or switches for receiving input signals, being characterised such that the said input interface circuitry is designed to be configurable, by means of configuration data supplied by the said configuration memory.
The said electronic controller further includes user interface circuitry connecting to one or more analog or digital input devices or switches for receiving user inputs and one or more display or audio devices for providing feedback to the user, being characterised such that the said user interface circuitry is designed to be configurable, by means of configuration data supplied by the said configuration memory.
The said electronic controller further includes power supply interface circuitry which connects to a power supply, monitors the power source conditions and provides control signals, being characterised such that the said power supply interface circuitry is designed to be configurable, by means of configuration data supplied by the said configuration memory.
The said electronic controller further includes network interface circuitry for interfacing to a network that provides unidirectional or bi-directional data exchange with other devices on the network.
The said configurable control circuitry and configurable output interface circuitry, are made configurable by providing, in each circuitry:
a plurality of predetermined circuit elements containing a plurality of known circuit element types each of which provides a specific function, the number and types of said circuit elements being chosen such that the functional requirements of each of the desired configurations are met,
a means for interconnecting the said circuit elements in required defined ways, each of which implements a desired set of functions by means of configuration data supplied by the said configuration memory.
The said configurable input interface circuitry, is made configurable by providing:
a plurality of predetermined circuit elements containing a plurality of known circuit element types each of which provides a specific function, the number and types of said circuit elements being chosen such that the functional requirements of each of the desired configurations are met,
a means for interconnecting the said circuit elements in required defined ways, each of which implements a desired set of functions by means of configuration data supplied by the said configuration memory.
The said configurable user interface circuitry, is made configurable by providing:
a plurality of predetermined circuit elements containing a plurality of known circuit element types each of which provides a specific function, the number and types of said circuit elements being chosen such that the functional requirements of each of the desired configurations are met,
a means for interconnecting the said circuit elements in required defined ways, each of which implements a desired set of functions by means of configuration data supplied by the said configuration memory.
The said configurable power supply interface circuitry, is made configurable by providing:
a plurality of predetermined circuit elements containing a plurality of known circuit element types each of which provides a specific function, the number and types of said circuit elements being chosen such that the functional requirements of each of the desired configurations are met,
a means for interconnecting the said circuit elements in required defined ways, each of which implements a desired set of functions by means of configuration data supplied by the said configuration memory.
The said control circuitry in another implementation is a Gate Array that is configured for desired functionality by the configuration data supplied by the said configuration memory.
The said control circuitry in another implementation is an embedded microcontroller with associated program memory containing a set of control programs the appropriate subset of programs being selected for desired functionality by the configuration data supplied by the said configuration memory.
The said control circuitry in another implementation is an embedded digital signal processor (DSP) with associated program memory containing a set of control programs the appropriate subset of programs being selected for desired functionality by the configuration data supplied by the said configuration memory.
The said control circuitry includes functionality for providing simple ON-OFF control action.
The said control circuitry includes functionality for providing Proportional, Integral, Derivative (PID) control action.
The said control circuitry includes a Real-Time-Clock (RTC) inorder to provide the control functions based on real-time events.
The said output interface circuitry is configurable for each of the outputs to provide a level or a pulsed output signal for controlling the load, by means of configuration data supplied by the said configuration memory.
The said output interface circuitry is configurable for each of the outputs to provide a triac-drive signal or a relay/contactor drive signal or a MOSFET/IGBT drive signal or a transistor drive signal for controlling the load, by means of configuration data supplied by the said configuration memory.
The said output interface circuitry is configurable for each of the outputs to provide a phase-angle control signal or integral cycle control signal or integral half-cycle control signal for controlling the load, by means of configuration data supplied by the said configuration memory.
The said input interface circuitry is configurable for each of the inputs to provide either a desired value of a constant current bias, or a balanced bridge interface, or an AC bias supply to the external signal source, by means of configuration data supplied by the said configuration memory.
The said input interface circuitry is configurable for each of the inputs to either perform analog-to-digital conversion for the case when the input signal is analog in nature, or process the signal without analog-to-digital conversion when the input signal is digital in nature, by means of configuration data supplied by the said configuration memory.
The said input interface circuitry is configurable for each of the inputs to perform debouncing for the case when the input signal is received from a mechanical switch, by means of configuration data supplied by the said configuration memory.
The said input interface circuitry is configurable for each of the inputs to include a filter in the processing of the received signal if so required, by means of configuration data supplied by the said configuration memory.
The said input interface circuitry is configurable for each of the inputs to include an averaging circuit in the processing of the input signal if so desired, by means of configuration data supplied by the said configuration memory.
The said user interface circuitry is configurable for each input to provide desired constant current bias if required by the external user input device, by means of configuration data supplied by the said configuration memory.
The said user interface circuitry is configurable for receiving user input though an infrared/ultrasonic/radio-frequency remote entry device, by means of configuration data supplied by the said configuration memory.
The said user interface circuitry is configurable for providing output signals for driving either an LED display, or a vacuum fluorescent display or an LCD display, by means of configuration data supplied by the said configuration memory.
The said user interface circuitry is configurable for providing output signals for driving either an multi-digit 7-segment display, or a bar-graph display, by means of configuration data supplied by the said configuration memory.
The said user interface circuitry includes the provision for generating tones and driving an audio transducer.
The said user interface circuitry includes the provision for generating synthesized voice output signals and driving an audio transducer.
The said power supply interface circuitry is configurable for monitoring the input a.c. supply voltage and providing a signal if the said a.c. supply voltage is less than or greater than defined limits, by means of configuration data supplied by the said configuration memory.
The said power supply interface circuitry is configurable for monitoring the input d.c. supply voltage and providing a signal if the said d.c. supply voltage is less than or greater than defined limits, by means of configuration data supplied by the said configuration memory.
The said power supply interface circuitry is configurable for monitoring the input a.c. supply voltage and providing a signal on every zero-voltage crossing of the input a.c. supply, by means of configuration data supplied by the said configuration memory.
The said network interface circuitry provides an interface to a TCP/IP network.
The said network interface circuitry provides an interface to a CAN Bus network.
The said network interface circuitry provides an interface to a BACNet network.
The said network interface circuitry provides an interface to a BlueTooth wireless network.
The said configuration memory is preferably a non-volatile memory.
The said Clock Generator is an oscillator with a frequency preferably in the range 32 KHz to 25 MHz.
In a washing machine, an electronic controller comprising configurable control circuitry, output interface circuitry, input interface circuitry, user interface circuitry, power supply interface circuitry, network interface circuitry and configuration memory, wherein the configuration data from the said configuration memory:
a) configures the configurable control circuitry which is based on an embedded microcontroller, to provide desired control functions using a selected set of stored control programs,
b) configures the configurable output interface circuitry for providing triac-controlled drive for the wash motor, and water-fill, drain and detergent-dispense solenoids,
c) configures the configurable input interface circuitry for providing bias drive for the water temperature sensor, and water level sensor and for enabling analog-to-digital conversion with suitable sensitivity offset and linearity correction, noise filtering and signal averaging for the analog signals received from these sensors,
d) configures the configurable user interface circuitry for interfacing to a keyboard on the control for receiving user selection input, and driving a digital LCD display and audio buzzer for providing feedback to the user,
e) configures the configurable power supply interface for monitoring the input a.c. supply voltage and providing a signal when the voltage is outside defined limits.
In a household refrigerator, an electronic controller comprising configurable control circuitry, output interface circuitry, input interface circuitry, user interface circuitry, power supply interface circuitry, network interface circuitry and configuration memory wherein the configuration data from the said configuration memory:
a) configures the configurable control circuitry which is based on an gate array logic, to provide temperature control functions using a selected set of stored control programs,
b) configures the configurable output interface circuitry for providing triac-controlled drive for the refrigeration compressor, defrost heater, and air-circulation blowers and dampers,
c) configures the configurable input interface circuitry for providing bias drive for the temperature sensors, and for enabling analog-to-digital conversion with suitable sensitivity offset and linearity correction, noise filtering and signal averaging for the analog signals received from these sensors,
d) configures the configurable user interface circuitry for interfacing to a keyboard on the control panel as well as an infra-red remote control device for receiving user selection input, and driving a digital LCD display and audio buzzer for providing feedback to the user,
e) configures the configurable power supply interface for monitoring the input a.c. supply voltage and providing a signal when the voltage is outside defined limits.
In an HVAC control system, an electronic controller comprising configurable control circuitry, output interface circuitry, input interface circuitry, user interface circuitry, power supply interface circuitry, network interface circuitry and configuration memory, wherein the configuration data from the said configuration memory:
a) configures the configurable control circuitry which is based on an embedded microcontroller, to provide airflow control and temperature control functions using a selected set of stored control programs,
b) configures the configurable output interface circuitry for providing brushless-DC motor drive for the airflow blower, triac-controlled drive for the air-conditioning compressor motor, and integral-cycle controlled drive for the air-conditioning heaters,
c) configures the configurable input interface circuitry for providing bias drive for the temperature sensor, airflow sensor and humidity sensor, and for enabling analog-to-digital conversion with suitable sensitivity offset and linearity correction, noise filtering and signal averaging for the analog signals received from these sensors,
d) configures the configurable user interface circuitry for interfacing to a keyboard on the control panel as well as an infra-red remote control device for receiving user selection input and driving a digital LCD display and audio buzzer for providing feedback to the user,
e) configures the configurable power supply interface for monitoring the input a.c. supply voltage and providing a signal when the voltage is outside defined limits.